On the evening of July 21, Mai Van Khiem, Director of the National Center for Hydro-Meteorological Forecasting under the Ministry of Agriculture and Environment, provided updates on Typhoon Wipha and important developments to watch.

Why did the typhoon weaken by three levels upon entering the Gulf of Tonkin?

On the morning of July 21, Typhoon Wipha passed over northern Leizhou Peninsula (China) and entered the Gulf of Tonkin with wind intensity at level 9. According to Khiem, this was somewhat “fortunate” as the storm weakened by three levels from its original level 12.

The weakening occurred because the typhoon moved northward as it approached the coast of Guangdong Province (China), reducing its friction with land and thus its energy source. This intensity was also one level lower than earlier predictions, which had forecast level 10 when the typhoon entered the Gulf.

By midday, the typhoon shifted slightly southward and its structure became more organized, intensifying back to level 10 with a continued strengthening trend.

“Satellite analyses suggest that the typhoon has strengthened since entering the Gulf of Tonkin. Forecasts indicate it could reach the upper end of level 10 or even level 11 before nearing the coastal area from southern Hai Phong to northern Thanh Hoa by midday tomorrow,” Khiem emphasized.

Peak danger period for wind and rain as the storm makes landfall

Khiem explained that Typhoon Wipha has a broad circulation. Even before it entered the Gulf of Tonkin, rain had already begun across the region on the evening of July 20 and continued overnight, even reaching coastal land areas. Hanoi also experienced storm clouds at its outer edge, though rainfall remained intermittent. Rainfall began to intensify from the afternoon of July 21.

As the storm approaches southern Hai Phong and northern Thanh Hoa, Hanoi could experience wind levels of 5–6, with gusts reaching level 8. Given the city’s many high-rise buildings, strong, localized storm winds could pose serious risks.

Khiem noted that the danger will escalate over time. From midday to afternoon on July 21, Quang Ninh and northeastern regions experienced heavy rain, with some locations receiving 175–200 mm. Bach Long Vi Island recorded winds at level 8, gusting to level 9, with expectations of further intensification overnight and into the morning.

From the afternoon until early morning of July 22, Quang Ninh and the Northeast will be the first areas to experience dangerous effects, with coastal winds reaching levels 7–8.

From tonight until 9 a.m. tomorrow, heavy rain is forecast for the Red River Delta and North Central Coast regions. The strongest winds are expected when the typhoon's center makes landfall in southern Hai Phong and northern Thanh Hoa between 10 a.m. and 3 p.m., with wind levels at 8–9 and central zones reaching level 10, gusting to levels 13–14.

Rainfall in Quang Ninh and the Northeast may persist until late July 22, then gradually decrease. In contrast, the Red River Delta, Thanh Hoa, and Nghe An will see rain intensify overnight and continue until the morning of July 23. As the storm's circulation moves into Upper Laos, rainfall intensity in these areas will diminish.

Areas at greatest risk of severe impact

According to Khiem, the areas most vulnerable to Typhoon Wipha include special zones such as Bach Long Vi, Co To, and Cat Hai, where high waves and tidal surges are expected.

The second most affected areas include Hai Phong, the Red River Delta, Thanh Hoa, and Nghe An, where the typhoon is expected to make direct landfall between southern Hai Phong and northern Thanh Hoa.

Starting from the evening and night of July 21, coastal regions from Quang Ninh to Nghe An will face strengthening winds at levels 7–9, with areas near the typhoon center reaching levels 10–11 and gusts up to level 14.

Inland areas like Hai Phong, Hung Yen, Bac Ninh, Hanoi, Ninh Binh, and Thanh Hoa may experience wind levels rising to 6, with gusts of 7–8. Level 10–11 winds could uproot trees, topple electric poles, damage roofs, and cause severe damage.

Khiem reported that in the two hours leading up to 6:30 p.m. on July 21, Typhoon Wipha had shown little movement. This warrants close monitoring to identify any changes that could alter the forecast trajectory.

Flooding and landslide danger zones

Khiem warned that the highest risk of flash floods and landslides is in Quang Ninh, due to ongoing and expected heavy rainfall. The second highest risk area is the western mountainous region of Thanh Hoa, including 20 communes, and 50 communes in Nghe An. Other at-risk areas include Muong Leo and Moc Chau in Son La and the southern part of Phu Tho (formerly part of Hoa Binh).

“We emphasize that heavy rains will persist through July 23. Even after the rain lessens, the risk of flash floods and landslides will remain high. Additionally, as the storm moves into Upper Laos, flash floods may occur in parts of Thanh Hoa,” Khiem noted.

As of 7 p.m. on July 21, the typhoon's center was approximately 90 km from Quang Ninh, 210 km from Hai Phong, 230 km from Hung Yen, and 260 km from Ninh Binh. Maximum sustained winds near the center reached levels 9–10 (75–102 km/h), with gusts up to level 13. The storm was moving west-southwest at about 10 km/h.

Due to Typhoon Wipha, Bach Long Vi experienced level 8 winds, gusting to level 10; Co To and Cat Ba recorded level 6 winds, gusting to level 8; and Mong Cai had level 6 winds, gusting to level 8.

Forecasts for 7 a.m. on July 22 indicate the storm's center will be located over the sea from Quang Ninh to Ninh Binh with winds at levels 10–11, gusting to level 14. By 7 p.m. that day, it is expected to be over land between Hai Phong and Thanh Hoa, with winds at level 9 and gusts up to level 11.

By 7 p.m. on July 23, the storm is projected to reach Upper Laos and weaken into a low-pressure system.

Bao Anh